Lesson Plan

2. Compare series and parallel circuits

KS3-22-02

Intent

Learning Intention

  • Compare series and parallel circuits
  • Construct series and parallel circuits
  • State the rules for how current behaves in a series and parallel circuit

National Curriculum

  • Electric current, measured in amperes, in circuits, series and parallel circuits, currents add where branches meet and current as flow of charge

Working Scientifically

  • Ask questions and develop a line of enquiry based on observations of the real world, alongside prior knowledge and experience
  • Interpret observations, identifying patterns and using observations to draw conclusions

Learning Outcomes

  • Compare series and parallel circuits
  • Construct series and parallel circuits independently
  • Make predictions about how current flows in a series and parallel circuit

Resources

Resources: Materials for the Mission Assignment, such as 2x 1.5V bulbs not LEDs, 4x wires, and 2x cells.

Handout: A diagram of the circuits the students must set up for their mission assignment.

Rocket words

  • series circuit
  • current
  • electron flow
  • parallel circuit
  • ammeter

Implementation

Prior Learning

Revise learning on series and parallel circuits from KS2. Students should recall that In a series circuit, the components are connected one after another, like a string of Christmas lights. However, in a parallel circuit, the components are connected side by side, like a spider web. Use the starter task to ensure all students have a similar understanding of series and parallel circuits before beginning the presentation.

Starter

Paul's cat, Murphy, knocked out one of the bulbs on his Christmas tree lights. Then, all the other bulbs went out. Ask the students to explain why the other bulbs went out.

Main Teaching

Use the presentation slides to explain how components can be arranged in a circuit. Then, go into detail on electrical currents, including how it is measured, what symbol is used and who discovered it. Connect this to ideas surrounding electrical resistance and use the prompt slides to create pupil discussion. Use the final slides to introduce voltage.

Career Film: Take a tour around Rolls Royce SMR's Heritage Museum in Derby to find out about Imane Holles's job. Imane works as the Senior Verification Engineer for Rolls Royce SMR.

Expert Film: This is Vaiva Nagtye. Vaiva works as the Lead Digital and Data Engineer for Rolls Royce SMR. Listen to Vaiva as she compares series and parallel circuits.

Mission Assignment

In this experiment, the students will be comparing a series and parallel circuit.

They do not need to set up the two circuits at the same time, but if they can, it will make the comparison easier.

  1. Using the handout, set up the circuits as shown in the diagram.
  2. Use an appropriate adjective to describe the brightness of the bulbs.
  3. Unscrew one bulb and describe what happens to the other bulb.

If you have a voltmeter, ammeter or multi-meter, you could also use this so the students can make some quantitative observations.

Differentiated tasks (Support/Challenge)

Support: Consolidate circuit symbols on mini whiteboards from the last lesson before starting practical work. Get the students to stand up and walk around the room to model electron flow in a series circuit.

Challenge: Ask the students to look at the circuits on the handout and describe how they work differently. What happens if you only close one switch?

Impact & Assessment Opportunities

Plenary

Ask the students to share their thoughts on which type of circuit they think would be more useful or efficient for different applications. 

Teacher Mastery

Current is the rate of flow of charge. This refers to how quickly electrons flow around a circuit. The more electrons and the quicker they move, the greater the current. It is measured in amps (A).

A series circuit is a circuit where all components are on one continuous loop and a parallel circuit is a circuit where components are connected on multiple loops.

In a series circuit, current is constant and there is only one way the current can flow. This is like a traffic jam where no car can go faster than any other car. In a parallel circuit where wires branch off (which we can think of as a junction), current is split into smaller parts that re-join together at another junction elsewhere in the circuit.

In a series circuit, if a component breaks then the entire circuit stops as the circuit is no longer complete. In a parallel circuit, if a component breaks then the current redirects to another loop and the circuit continues - depending on where the break is made.